I dont know how to open the side bar
There is a ridged corner in the 3D window (top-right), move the mouse there and when you get the "cross" mouse icon just drag it to the left (it seems that you have already performed this step). 

After that, you will have an editor type selector with a "cube" icon in the left bottom corner, click on that and, from the drop-down, choose the icon next to "properties".

Alternatively,
Just save your work as it is and go to File then Load factory settings, then open your file again, unchecking the "Load UI" checkbox in the File browser.